This research aims to enhance the autonomy of four populations of vulnerable subjects of research: adolescent patients; patients with HIV infection; patients with mental illness; and geriatric patients. The vulnerability of these and other populations results from patient-level traits which may not be malleable and barriers to the exercise of autonomy in the consent process, which may be malleable. Research will identify and remove barriers to the exercise of autonomy from the consent process and measure the effects on the components of autonomy (intentionality, understanding, and non-control) and on perceived reduction of barriers. Two interrelated objectives of this project are: (1) Design and pilot a trial of interventions to remove barriers to the exercise of autonomy from the consent process. These barriers will be identified by focus-group research with vulnerable individuals, their surrogates, and experienced clinical investigators to augment the current fund of knowledge about such barriers and survey-questionnaire research to quantify the prevalence and importance of these barriers. Prevalent and important barriers will be targeted by the interventions; (2) Measurement research to develop and validate instruments to measure the components of autonomy in vulnerable individuals and instruments to measure perception of barriers. Nine focus groups will be conducted, eight with subjects or their surrogates and one with experienced investigators for a total of 108 subjects, and analyzed following accepted qualitative methods. Survey-questionnaires, incorporating these results, will be administered to a sample of 132 subjects, and analyzed following accepted quantitative methods. Instruments for the measurement of intentionality, understanding, non-control, and the perception of barriers will be adapted from existing instruments or developed on the basis of existing literature. Instrument validation will follow accepted methods with 298 subjects. One intervention will be developed and piloted for each population with a total of 80 subjects, with trends toward enhanced autonomy and reduced perception of barriers measured.